Method for manufacturing dry shaver-cutter unit

ABSTRACT

A method is provided for forming the cutter unit of a dry shaver by winding an elongated strip of cutter material edgewise into a helical configuration. The strip is initially formed with longitudinally extending undulations or waves and after it is helically wound a longitudinally extending support member is provided centrally of the helical configuration. The radially outermost edge of the helically wound strip extends beyond the support member to form the cutting edge of the unit.

O United States Patent 11 1 [111 3,927,581

Kolodziej Dec. 23, 1975 METHOD FOR MANUFACTURING DRY 2,178,669 11/1939 Lougheed 30/346.51 x SHAVER CU1TER UNIT 3,027,635 4/1962 Frith 30/346.51 X 0 3,045,344 7/1962 Cholet 30/346.5l X Inventorl J y Antoni Kolodliej, Stobhill, 3,060,572 10/1962 Duncan 30/346.51 x

Northcumberland, England [73] Assignee: Ronson Products Liniited, England Primary Examiner-Leonidas Vlach'os Attorney, Agent, or Firm-Toren, McGeady and [22] F1led: Mar. 28, 1974 Stangel. [21] Appl. No.: 455,535

[57] ABSTRACT [30] Foreign Application Priority Data A method is provided for forming the cutter unit of a Apr. 2, 1973 United Kingdom .l 15759/73 dry Shaver by winding Flongated StriPPf cutter terial edgewise nto a hellcal configuranon. The stnp 52 us Cl 76/104 76/DIG' 30/346 is initially formed with longitudinally extending undu- 51 Int. (:1. B21K 11/00; 3263 19/04 lations of after it is helically Wound a longi- [58] Field Of Search 76/104 R, DIG. 8' mdinally extending Support member is Provided 30 34 51; 29 73; 5 164/98 trally of the helical configuration. The radially outermost edge of the helically wound strip extends beyond [56] References Cited the support mernber to form the cutting edge of the UNITED STATES PATENTS 2,026,630 l/l936 Harris 30/34651 x 12 Cl 4 Drawing Figures US. Patent Dec. 23, 1975 3,927,581

METHOD FOR MANUFACTURING DRY SHAVER-CUTTER UNIT BACKGROUND OF THE INVENTION The-present invention relates generally to cutting units for dry shavers and more particularly to a dry shaver of the type wherein the cutting unit is reciprocally located within a perforated foil.

In this type of shaver, the perforated foil is placed in contact with the skin and hair protruding through the perforations of the foil is cut by the shearing action occurring between the cutting edge of the reciprocated cutter unit and the edges of the perforations.

An important consideration in such shavers requires that the cutter unit be arranged to operate in an efficient manner. It has been found that a cutter unit formed from a plurality of parallel blades mounted in a rigid support will operate most efficiently. However, although such a cutter unit exhibits increased efficiency it involves an arrangement which has been found difficult and costly to manufacture.

In one method of construction offering some manufacturing advantages, a wire is wound on a mandrel having a circular cross section with a subsequent grinding operation being performed to provide a cutting edge for the cutter unit. Cutters made in accordance with this prior art method of manufacture have not, however, been found satisfactory primarily due to the fact that it is difficult to grind or otherwise provide a cutting edge in the unit. Furthermore, it has been found that the blades themselves develop an inherent weakness. 1 The present invention is directed to a method for manufacturing a cutting unit of this type which will exhibit superior operating characteristics and which will not create adverse manufacturing problems.

SUMMARY OF THE INVENTION which the inner edge of the strip is wound in a helical pattern. The strip may be wound about the mandrel with sufficient tightness such as to enable the mandrel to serve as a central support member for the cutter unit. Alternatively, the cutter strip may be adhered to the mandrel upon which it is wound.

' By another aspect of the invention, the helically wound strip may be removed from the mandrel after the winding operation and a support structure formed from molded plastic material or metal may be subsequently provided. Molding of the plastic or metal support member within the helical configuration formed by the cutter strip will operate to impart structural rigidity to the unit and to form the unit as a rigid body. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a perspective view depicting a portion of a metallic ribbon or cutter strip used in the method of the present invention in constructing an inner cutter unit;

FIG. 2 is a perspective diagram showing the shape of a portion of the cutter strip after it has been wound in a helical configuration and depicting the distortion which occurs in the undulations or waves of the cutter strip or ribbon which has been wound edgewise to form the helix:

FIG. 3 is a perspective view of a cutter strip wound in the form of a helix; and FIG. 4 is a perspective view of a portion of a cutter unit comprising a cutter strip wound in helical form and having a molded support member within which the cutter strip is embedded.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, wherein like reference numerals refer to similar parts throughout the various figures thereof, there is shown in FIG. 1 a cutter strip or ribbon 1 which is utilized in the performance of the method of the present invention to form the cutter unit. The strip 1 may be made of any suitable cutter material and it is formed with undulations or waves which extend longitudinally of the strip throughout its length. The strip 1 comprises a pair of longitudinal edges 2 and 3 and it will be seen that when the strip is viewed edgewise looking in the direction of the arrow X the edge 2 of the strip will be formed with a wave pattern which may be generally described as sinusoidal in nature. In FIG. 1, the strip is shown before it is wound in a helical arrangement and it will be noted that the wave pattern of the edges 2 and 3 is substantially identical with the strip in this condition.

In the formation of the cutter unit according to the present invention, the strip shown in FIG. 1 is first wound edgewise into a helical configuration 4, as shown in FIG. 3. With the strip wound in the form shown in FIG. 3, the edge 3 will be located radially inwardly of the edge 2 relative to the overall pattern of the helix which is formed.

In the performance of this winding operation, a mandrel (not shown) may be used and the helix 4 may be formed by winding the strip 1 with the edge 3 abuting the mandrel. The mandrel used will thus serve as a guide structure for winding of the helix 4. The mandrel used may be of a circular cross section having a relatively small radius and because of the form of the strip or ribbon l, the bending or winding operation may be accomodated without damage to the cutter stripl.

The effect of bending or winding the strip 1 into the helical configuration 4 is depicted in FIG. 2. It will be seen that when the winding operation has been performed, the wave pattern of the inner edge 3 will be different from the wave pattern of the outer edge 2. That is, the inner edge 3 will have a wave amplitude which is greater than the wave amplitude of the outer edge 2. Furthermore, the wave lengths of the wave formations of the edges 2 and 3 will be different, with the outer edge 2 having a longer wave length than the inner edge 3. Thus it will be seen that compared with the strip formation shown in FIG. 1, wherein both the edges 2 and 3 are similarly shaped, winding of the strip into its helical shape will cause distortion of the wave pattern of the edges 2 and 3, with the edge 3 having a resultant increase in its amplitude and decrease in its wave length while the edge 2 is distorted in a manner increasing its wave length but decreasing its amplitude.

The mandrel which is used as a guide member in winding the strip, may also be ultimately utilized as a centrally located support member for the helically wound cutter strip. In such a case, the strip 1 may be wound tightly upon the mandrel, which may be provided as a hollow body, so that the mandrel forms part of the finished unit and operates to support the helix. Alternatively, the helix 4 may be removed from the mandrel after the winding operation in which case it will be in the condition depicted in FIG. 3. In this condition, absent the central support member, the helical cutter strip would have the characteristics of a helical spring of similar proportion but it will clearly not comprise a rigid structure. Accordingly, the helix may be subsequently partly encased or embedded in a metal or plastic support body in order to impart sufficient structural rigidity to the finished unit. Part of a cutter unit formed by such a procedure is depicted in FIG. 4 which comprises a molded support member 5 located internally and centrally of the helix 4. After it has been embedded in the molded support member 5, the outer edges of the cutter strip may be ground to provide the required cutting edges. It will be seen that the support member 5 extends to more than half the diameter of the helix 4. In some circumstances, the support material may be formed to extend to a small distance inwardly from the outer edge of the cutter strip throughout the helix so that a solid core is produced for the cutter unit. With such a configuration, the outer edge of the helix or strip would be exposed to form a suitable cutting edge for the cutter unit.

From the foregoing it will be seen that in accordance with the method of the present invention, a structurally stable cutter unit may be formed in a manner involving manufacturing procedures which are relatively simple and inexpensive. The cutter strip 1 may be wound about a mandrel which may either be used as a guide body or which may also be used to form the central support core of the cutter unit by tightly winding and- /or adhering the cutter strip directly to the mandrel. Alternatively, the mandrel may be removed after helical winding of the cutter strip and a plastic or metallic inner core may be molded with the helically formed cutter strip imbedded therein to produce a solid, rigid cutter unit exhibiting suitable structural characteristics.

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

I claim:

1. A method for making a cutter unit for a dry shaver assembly comprising the steps of providing an elongated strip of cutter material, forming in said strip undulations extending in a longitudinal direction of said strip, winding said strip edgewise into a helical configuration, providing a longitudinal support member for said strip, and embedding portions of said strip in said longitudinal support member to mount said strip thereupon.

2. A method according to claim 1 wherein said longitudinal member is formed of plastic material having portions of said wound helical strip embedded therein.

3. A method according to claim 1 wherein said longitudinal member is formed of metallic material having portions of said wound helical strip embedded therein.

4. A cutter unit for a dry shaver assembly comprising an elongated strip of cutter material, said strip being wound edgewise in a helical configuration, undulations extending in a longitudinal direction of said strip, and a longitudinal support member having parts of said strip embedded therein for mounting said strip upon said support member.

5. A method according to claim 1 wherein said helical configuration is formed by winding said strip about a mandrel.

6. A method according to claim 5 wherein said helically formed strip is adhered to said mandrel, with said mandrel forming the longitudinal support member for the finished cutter unit.

7. A method according to claim 6 wherein said mandrel consists of a hollow body.

8. A method according to claim 1 wherein said longitudinal member is formed by molding.

9. A method according to claim 1 wherein said strip comprises a length dimension which is greater than a width dimension of said strip, with a pair of generally parallel edges extending in the direction of said length dimension on opposite sides of said strip, said longitudinally extending undulations being formed so that said strip defines a waved configuration having a wave length and amplitude substantially idential along both said edges of said strip before said winding step is performed, and wherein after performance of said winding step said strip is shaped with the wave length and amplitude of the wave pattern extending along one of said edges being increased and decreased, respectively, while the wave length and amplitude defined along the other of said edges is decreased and increased, respectively.

10. A method according to claim 9 wherein said edgewise wound strip is formed with one of said edges located radially inwardly of the other of said edges and wherein said radially innermost edge is formed with a wave configuration having a greater amplitude and a lesser wave length than the amplitude and wave length of the other outermost edge.

11. A method according to claim 1 wherein said support member extends from the center of said helical configuration through more than half the diameter of said helix.

12. A method according to claim 11 wherein said support body extends proximate the radially outer edge of said helically wound strip throughout the length of said helix. 

1. A method for making a cutter unit for a dry shaver assembly comprising the steps of providing an elongated strip of cutter material, forming in said strip undulations extending in a longitudinal direction of said strip, winding said strip edgewise into a helical configuration, providing a longitudinal support member for said strip, and embedding portions of said strip in said longitudinal support member to mount said strip thereupon.
 2. A method according to claim 1 wherein said longitudinal member is formed of plastic material having portions of said wound helical strip embedded therein.
 3. A method according to claim 1 wherein said longitudinal member is formed of metallic material having portions of said wound helical strip embedded therein.
 4. A cutter unit for a dry shaver assembly comprising an elongated strip of cutter material, said strip being wound edgewise in a helical configuration, undulations extending in a longitudinal direction of said strip, and a longitudinal support member having parts of said strip embedded therein for mounting said strip upon said support member.
 5. A method according to claim 1 wherein said helical configuration is formed by winding saId strip about a mandrel.
 6. A method according to claim 5 wherein said helically formed strip is adhered to said mandrel, with said mandrel forming the longitudinal support member for the finished cutter unit.
 7. A method according to claim 6 wherein said mandrel consists of a hollow body.
 8. A method according to claim 1 wherein said longitudinal member is formed by molding.
 9. A method according to claim 1 wherein said strip comprises a length dimension which is greater than a width dimension of said strip, with a pair of generally parallel edges extending in the direction of said length dimension on opposite sides of said strip, said longitudinally extending undulations being formed so that said strip defines a waved configuration having a wave length and amplitude substantially idential along both said edges of said strip before said winding step is performed, and wherein after performance of said winding step said strip is shaped with the wave length and amplitude of the wave pattern extending along one of said edges being increased and decreased, respectively, while the wave length and amplitude defined along the other of said edges is decreased and increased, respectively.
 10. A method according to claim 9 wherein said edgewise wound strip is formed with one of said edges located radially inwardly of the other of said edges and wherein said radially innermost edge is formed with a wave configuration having a greater amplitude and a lesser wave length than the amplitude and wave length of the other outermost edge.
 11. A method according to claim 1 wherein said support member extends from the center of said helical configuration through more than half the diameter of said helix.
 12. A method according to claim 11 wherein said support body extends proximate the radially outer edge of said helically wound strip throughout the length of said helix. 